GroupShare REST API token

Hello,

I am trying to get GroupShare's REST API token, but getting an error.

I tried to send request with PHP cURL and with PowerShell script from here:

https://community.sdl.com/phase_2_groups/sdl_openexchange_developers/f/57/p/2777/10371.aspx#10371

Both requests are returning same error: "Error occurred while sending a direct message or getting the response."